DISTRIBUTION OF BUTTERFLIES IN THE NEW WORLD 359 



seven genera display a common equatorial distributional pattern in 

 which the distribution would be panequatorial were it not that the 

 northern range stops at 10° N. Lat., that is, at the Isthmus of Pan- 

 ama. Since these are usually well-adapted tropical types existing at 

 low elevation, there is no discernible reason for this abrupt termina- 

 tion except for the few that cannot cross the Andes from the eastern 

 to the western tropical regions in Colombia or Venezuela. The two 

 pierid genera of this category are Leucidia and Leodonta (Fig. 4). 

 Complementary distributions from 10° N. Lat. northward are less 

 common. These are in effect circum-Caribbean types, which are 

 represented in the Pieridae by Kricogonia and Nathalis (Fig. 4), the 

 latter of which reaches as far south as 5° N. Lat. In the Eiichloinae 

 three genera, Eroessa, Andina, and Phalia (Fig. 5), are restricted to 

 southern latitudes at high elevations. 



In the Danaidae (Figs. 5-7), 19 out of a total of 34 genera fit into 

 neither the northern nor the panequatorial pattern. Since all these 

 are tropical, the reason for their restricted range is not immediately 

 apparent. Ten of the 19 reach their northern limit at 10° N. Lat., 

 but most of these also do not extend far southward. The other 9 are 

 limited to belts of varying degrees of latitude in the vicinity of the 

 equator. This would seem to indicate that temperature is not the 

 limiting factor in their distribution. 



In the Satyridae (Figs. 7-12), fully 60 of the 85 genera have ranges 

 that do not fit into the two major categories. The Panamanian limit 

 (10° N. Lat.) characterizes only 18 of the genera. The others are 

 limited in various ways. The most common limitation in this family 

 is restricted altitudinal range for a short latitudinal distance in the 

 equatorial Andes. This family is rich in genera of limited distribu- 

 tion in the Andes and in the Central American Cordillera. Included 

 are genera of very small range at almost every latitudinal belt from 

 30° to 40° N. Lat. to 30° to 40° S. Lat. In fact, this family has more 

 genera than any other, and most of them are limited in range. No 

 other family has so many genera (fully 14) restricted to a south 

 latitudinal distributional range or so many (22) restricted to a range 

 of less than 10° of latitude. 



In the Brassolidae (Fig. 12), of the four genera not included in the 

 panequatorial distributional pattern, two cease their northern range 

 at the Panamanian 10° N. Lat. limit, and two are restricted to a 

 narrow (10°) range south of the Tropic of Capricorn. 



